title: A Mycobacterium marinum TesA mutant defective for major cell wall-associated lipids is highly attenuated in Dictyostelium discoideum and zebrafish embryos.
abstract: Infection of the zebrafish with Mycobacterium marinum is regarded as a well-established experimental model to study the pathogenicity of Mycobacterium tuberculosis. Herein, a M. marinum transposon mutant library was screened for attenuated M. marinum phenotypes using a Dictyostelium discoideum assay. In one attenuated mutant, the transposon was located within tesA, encoding a putative type II thioesterase. Thin-layer chromatography analyses indicated that the tesA::Tn mutant failed to produce two major cell wall-associated lipids. Mass spectrometry and nuclear magnetic resonance clearly established the nature of missing lipids as phthioglycol diphthioceranates and phenolic glycolipids, respectively, indicating that TesA is required for the synthesis of both lipids. When injected into the zebrafish embryo bloodstream, the mutant was found to be highly attenuated, thus validating the performance and relevance of the Dictyostelium screen. Consistent with these in vivo findings, tesA::Tn exhibited increased permeability defects in vitro, which may explain its failure to survive in host macrophages. Unexpectedly, virulence was retained when bacteria were injected into the notochord. Histological and ultrastructural studies of the infected notochord revealed the presence of actively proliferating mycobacteria, leading to larval death. This work presents for the first time the notochord as a compartment highly susceptible to mycobacterial infection.
authors.affiliation: Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier II et I, CNRS; UMR 5235, case 107, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France.
authors.forename: Laeticia
authors.initials: L
authors.lastname: Alibaud
authors.forename: Yoann
authors.initials: Y
authors.lastname: Rombouts
authors.forename: Xavier
authors.initials: X
authors.lastname: Trivelli
authors.forename: Adeline
authors.initials: A
authors.lastname: Burguière
authors.forename: Suat L G
authors.initials: SL
authors.lastname: Cirillo
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Cirillo
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Dubremetz
authors.forename: Yann
authors.initials: Y
authors.lastname: Guérardel
authors.forename: Georges
authors.initials: G
authors.lastname: Lutfalla
authors.forename: Laurent
authors.initials: L
authors.lastname: Kremer
mesh_terms: D000818:Animals; D002473:Cell Wall / Q000201:enzymology*; D002478:Cells, Cultured; D004251:DNA Transposable Elements; D004023:Dictyostelium / Q000382:microbiology*; D006017:Glycolipids / Q000172:deficiency* / Q000235:genetics; D008055:Lipids / Q000172:deficiency* / Q000235:genetics*; D008264:Macrophages / Q000382:microbiology; D009154:Mutation; D009164:Mycobacterium Infections / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D019910:Mycobacterium marinum / Q000201:enzymology* / Q000235:genetics; D009672:Notochord / Q000382:microbiology; D010170:Palmitoyl-CoA Hydrolase / Q000235:genetics / Q000378:metabolism*; D015027:Zebrafish / Q000196:embryology / Q000382:microbiology*
chemical_list: D004251:DNA Transposable Elements; D006017:Glycolipids; D008055:Lipids; D010170:Palmitoyl-CoA Hydrolase